Kelly bushing



Patented Dec. 20, 1938 UNITED STATES KELLY BUSHING William A. Vck,

Application August 3,

4 Claims..

This invention relates to Well drilling apparatus and relates more particularly to a drive bushing or Kelly bushing for use in the rotary table of a well drilling rig. A general object of 5 this invention is to provide a practical, effective and improved roller type Kelly bushing.

In the rotary method of well drilling a drive bushing or Kelly bushing is arranged in the rotary table to cooperate with the grief stem or kelly of the drilling string for the purpose of imparting rotation to the string. The engagement between the Kelly bushing and the kelly is such that the drill stem may be moved vertically while the driving or rotative engagement is maintained ings embodying rollers for contacting the kelly have been introduced to lessen the wear and friction between the kelly and the bushing parts and to assure smoother movement of the drilling string and more positive control of the drilling string.

Grief stems or kellys of the type now in general use are substantially square in transverse cross section, having four principal side surfaces disposed at substantially 90 to one another. The Kelly bushings that have been introduced employing rollers have sets or series of cylindrical rollers arranged to dene a square opening for receiving the kelly. The rollers are of necessity related to receive the kelly with suitable clearance and when rotation of the bushing is initiated each cylindrical roller moves into driving contact with a flat face of the kelly. Due to the essential clearance just referred to and the cylindricaI configuration of the rollers, each roller, of the previously introduced, Kelly bushings has only line contact or very limited contact with a surface of the kelly. When wearing of the kelly and rollers occurs this action is more pronounced and it has been observed that the rollers each have a very limited surface portion at one end only in contact with the kelly when the bushing is driving or turning the string. The very limited engagement of the rollers with the kelly results in' the improper distribution of the driving forces and concentration of the wear on very limited areas of the kelly and the bushing rollers.

Another object of this invention is to provide a Kelly bushing embodying rollers for cooperating with the kelly which rollers have extensive portions of their surfaces in full driving contact with the faces of the kelly thereby assuring a more uniform distribution of the driving forces between the bushing and the kelly. Kelly bush- Long Beach, Calif.

1936, Serial No. 94,007

(Cl. Z- 23) and appreciably lessening the wear on the kelly and the rollers.

Another object of this invention is to provide an improved Kelly bushing embodying antifriction rollers shaped and positioned to have extensive driving or force transmitting engagement` with the surfaces of the kelly.

Another object of this invention is to provide a Kelly bushing embodying rollers having pitched or tapered surfaces that come into full even force transmitting engagement with the kelly when the play or clearance is taken up at the initiation of movement of the rotary table, thereby reducing wear and friction and assuring a better distribution of the driving forces.

Another object of this invention is to provide a Kelly bushing of the character mentioned in which the engagement between the rollersV and the kelly cannot produce longitudinal grooves or limited areas of excessive wear on the kelly.

Another object of this invention is to provide an improved Kelly bushing of the character mentioned in which the rollers are supported for independent rotation in a novel and particularly dependable manner and may be easily and inexpensively replaced when worn.

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawing. in which:

Fig. 1 is a side elevation of the improved rotary table bushing of the present invention illustrating it in the operative position in the master bushing of a rotary table. Fig. 2 is a top or plan view of the assembly being a view taken as indicated by line 2-2 on Fig. 1. Fig. 3 is a transverse detailed sectional view taken as indicated by line 3 3 on Fig. 1. Fig. 4 is an enlarged vertical detailed sectional View taken as indicated by line 4-4 on Fig. 1 and Fig. 5 is an enlarged top or plan view of one of the cages and its rollers removed frorn the body.

The drive bushing or Kelly bushing of the present invention is intended for use in the rotary table of a well drilling rig for engaging and driving the grief stem or kelly of the drilling string. In the following detailed disclosure I will describe a typical preferred form of the invention intended for arrangement in a typical master bushing of a rotary table and as employed in connection with a typical grief stem or kelly. It is to be understood that the invention is not to be construed as limited or restricted to the specific form or application about to be described.

Figs. 1 and 2 of the drawing illustrate a portion of a typical rotary table T having the usual central opening O. A master bushing B is arranged in the opening O and is seated therein to turn with the rotary table T. In accordance with the usual practice the bushing B has a central longitudinal opening I6. The principal or major portion of the opening I0 is round in horizontal section and is downwardly and inwardly tapered or reduced in diameter. The upper portion IIIa of the opening I0 is polygonal in horizontal section. In the particular case illustrated the upper portion Illa of the bushing opening I0 is substantially square in horizontal cross section having four flat surfaces II disposed at substantially to one another. The kelly K may be considered as connected with the upper end of a rotary well drilling string and as shown in the drawing extends centrally through the vertical opening I0 of the bushing B.

The improved Kelly bushing of the present invention includes, generally, a body I5 to be arranged in the upper portion Il)a of the bushing opening I0, a plurality of cages I6 in the body I5, rotatable members or rollers II mounted in the cages I6 to cooperate with the kelly K and means I8 for retaining the cages I6 in the body I5.

The bushing body I5 is intended to be supported in the upper portion Illa of the bushing opening I0 to rotate with the bushing Band the table T. The body I5 is provided to house or carry the cages I6 and is hollow or tubular having a central longitudinal opening I9. The body I5 is shaped to properly cooperate with the opening I0. The body I5 has a tapered lower portion 2| of round horizontal cross section to iit the opening l0 and a main body portion 22 of polygonal or square horizontal cross section to t the upper portion Illa of the opening I 0. The body I5 is preferably comparatively long to accommodate large cages I6 and its main portion I2 may project frorn the upper surface of the bushing B as illustrated in the drawing. The opening I 9 in the body I5 is provided to pass the kelly K and to house the cages I6. 'Ihe opening I9 extends vertically through the body I5 from one end to the other and is such that the roller carrying cages I6 may be passed into it from its upper end. The opening I9 of the body I5 is preferably polygonal having four principal flat vertical walls 23 to have driving contact with the cages I6. An

inwardly projecting stop or supporting ilange 24 is provided on the body I5 to project into the opening I 9 adjacent its lower end.

The cages I6 are provided to mount or carry the rollers I'I within the body I5. In the embodiment of the invention illustrated in the drawing there are four like cages I6 arranged within the body I5 to bear against its internal walls 23. The cages I6 are substantially rectangular in conguration having spaced vertical sides 25 and horizontal ends 26 extending between and connecting the sides 25. The lower ends 26 of the cages I6 are adapted to rest or bear on the flange 24. The cages I6 are proportioned so that their upper ends 26 have their upper surfaces substantially iiush with the upper end of the body I5 when the cages are resting on the flange 24. In accordance with the invention the four cages I6 nest or mesh with one another to be held in their proper positions against the body walls 23. A flat sided vertical recess 21 is provided in an inner corner portion of each cage I6 to receive the corner portion of an adjacent cage. The cages I6 having their corner portions cooperating with the recesses 2l of adjacent cages form a substantially rigid interlocked assembly which bears outwardly against the body Walls 23. The bushing body I5 may have diagonal corner portions 28 in the corners of the body opening I9 to aid in positioning the cages I6 and to strengthen the general structure.

The rotatable members or rollers I'I are provided on the cages I6 to engage the surfaces II of the kelly K. The rollers I1 are horizontally disposed in the cages I6 and are arranged to project from their inner sides to contact the kelly K. In accordance with the invention there is a plurality or series of rollers II provided on each cage I6. The rollers I'I are spaced apart vertically and are in vertical alignment. In practice the rollers Il' may be equally spaced apart vertically. However, it may be preferred to space the rollers I'I unequally to prevent ridging or grooving of the kelly K. The several rollers Il are preferably identical and preferably have flat normal ends. The rollers I'I are arranged in the cages I6 to have their ends at or adjacent the inner surfaces of the cage sides 25.

The rollers I'I are preferably carried by shafts or pins 30. Each roller Il is provided with a central longitudinal opening v3| extending through it from one end to the other. The supporting pins 30 are arranged through the openings 3I to project beyond the opposite ends of the rollers. In accordance with the invention the pins 36 are rigid with the rollers II. In practice the rollers I'I may be shrunk on the pins 36 to be rigidly secured to the pins. The projecing end portions of the pins 30 are rotatably received in openings 32 in the sides 25 of the cages I6. 'I'he openings 32 are horizontally aligned whereby the rollers I 'I are supported for rotation about horizontal axes. The roller carrying pins 3i) are locked or held against longitudinal movement. The end faces of the adjacent cages I6 partially close or extend across the outer ends of the openings 32 to definitely hold the pins 36 against longitudinal movement. Fig. 3 of the drawing illustrates this relationship between the cages and pins 30. The pins 36 are rotatably supported in the cages I6 to carry the rollers I1 so that they have the desired contact with the kelly K as will be subsequently described. The invention preferably includes means for lubricating the roller carrying pins 36. Vertical openings 33 are provided in the end parts or ends 25 of the cages I6 and communicate with the several pin carrying openings 32. Grease gun fittings 34 are provided at the upper ends of the openings 33 whereby lubricant may be supplied to the openings 33 under pressure to lubricate the projecting end portions of the pins 30.

The shape of the rollers I'I and the relationship of the rollers to the kelly are important features of the invention. In accordance with the invention the rollers I'I are formed or shaped to each have extensive cooperation with a side or surface II of the kelly K. The rollers I1 are frustoconical or tapered, each having a longitudinally tapered peripheral surface 35 for contacting a surface II of the kelly K when the rotary table T is turned in the forward or right-hand direction indicated by the arrow in Fig. 3 of the drawing. The surfaces 35 are smooth and regular and preferably extend to the advancing or forward ends of the rollers Il relative to the forward direction of rotation of the table T. The surceive the ring 4I).

faces 35 have a relatively slight taper or pitch, the pitch of the surfaces being dependent to some extent upon the clearance between the kelly K and the rollers I1. It is preferred that the surfaces 35 be of Substantial extent or length. The rollers I1 are preferably proportioned so that their surfaces 35 have their inner ends or their trailing ends, relative to the direction of forward rotation of the table T, at the centers of the adjacent surfaces Il of the kelly K when the rollers are in contact with the kelly. In the arrangement illustrated in the drawing Where the rollers I1 have their opposite ends unequally spaced from the adjacent sides of the kelly K the driving surfaces 35 have a length greater than one half the length of the rollers. The taper or pitch of the surfaces 35 is such that the surfaces come into full engagement with the surfaces I I of the kelly K when rotation of the table T is initiated'. The surfaces 35 are sufficiently long to have engagement with the kelly surfaces II throughout at least one half of their widths.

The trailing end portions of the rollers II relative to the forward direction of rotation of the table T are adapted to have cooperation with the kelly K when the table T is turned in a left hand or reverse direction. The surfaces 36 occurring on the trailing end portions of the rollers I1 are preferably tapered in the opposite direction to the surfaces 35. The taper of the surfaces 36 is substantially equal to the taper of the surfaces 35 although the surfaces 36 are of less length than the surfaces 35 as described above. The surfaces 36 may extend from the inner ends of the driving surfaces 35 to the trailing ends of the rollers I1. The tapered surfaces 35 and 36 join at circumferential lines 31. 'I'he rollers I1 are rotatably supported in the cages I6 so that the lines 31 have only slight or essential clearance with the kelly K. Accordingly, when the table T is turned in the direction indicated by the arrow in Fig. 3 the driving surfaces 35 almost immediately come into full cooperation with the surfaces II of the kelly K. It is preferred to make the clearance between the lines 31 and the kelly K slight so that the taper of the surfaces 35 may be gradual as illustrated.

The means I8 is provided to lock or retain the cages I6 in the body I5. The means I8 preferably includes a simple retaining member in the form o-f a ring 4U. The ring 40 is removably secured to the upper end portion of the body I5. The extreme upper end part of the body I5 has a cylindrical outer surface and is screw threaded to re- The ring 40 is provided with an inwardly projecting ange 4I which is adapted to engage the upper end of the body I5 when the ring is fully threaded on the body. The flange 4I is proportioned to extend inwardly beyond the upper end of the body I5 to project over and engage the upper ends of the cages I6. The anged ring 4B thus operates to hold the cages I6 in their proper positions in engagement with the flange 24. The ring flange 4I is proportioned so that it does not engage or interfere with the kelly K and so that it does not render the grease fittings 34 inaccessible. The retaining ring 4I] is preferably locked or set in position so that it cannot work loose. Diametrically opposite outwardly projecting lugs 42 are provided on the ring 4U and similar lugs 43 are provided on the four corners of the main portion 22 of the body I5. Bolts 44 are removably arranged through openings in the lugs 42 and 43 to definitely lock the ring 40 against unthreading.

During operation of the apparatus illustrated in the drawing the rotary table T may be rotated in the direction indicated by the arrow in Fig. 3 to drive or rotate the drilling string. As above described, the body I5 of the Kelly bushing turns with the table T and the rollers I1 rotatably mounted within the body I5 cooperate with the kelly K to transmit the driving or rotative forces to the kelly. The kelly K may be moved or shifted vertically during its rotation by the Kelly bushing and the rotation transmitting rollers I1 being rotatable offer a minimum of resistance to such vertical shifting of the kelly. Accordingly vertical shifting of the kelly K during its rotation does not impose additional weight or load on the rotary table and the rollers I 1 allow the drill string to be moved vertically in a uniform or regular manner for the better contro-l of the tools connected therewith. The four series of vertically spaced rollers I1 are rotatably carried in the cages I6 to contact the four surfaces I I of the polygonal kelly K. As described above, the rollers I1 are shaped to maintain long or extensive surfaces 35 in driving engagement with the Kelly surfaces II.

Prior to rotation of the table T the parts may be in the relative positions illustrated in Fig. 2 of the drawing where the lines 31 have slight clearance with the sides of the kelly K and the surfaces 35 and 36 of the rollers I1 are out of contact with the kelly. When rotation o-f the table T is started in the direction indicated by the arrow in Fig. 2 the initial movement of the table brings the roller surfaces 35 into full engagement with the surfaces II of the kelly K. This relationship between the rollers I1 and the kelly K is illustrated in Fig. 3 of the drawing. It will be observed that the surfaces 35 have extensive engagefrnent with the surf-aces II of the kelly K being pitched or tapered so that they engager the kelly throughout their lengths. Accordingly, the rollers I1 maintain extensive surfaces in driving engagement with the kelly K for the transmission of rotation to the kelly. As described above, the surfaces 35 of the rollers I1 may engage the Kelly surfaces II throughout one half of their widths or more. The pluralities of spaced rollers I1 having the extensive surfaces 35 in full contact with the kelly K dependably drive or rotate the kelly. As the individual rollers I1 are independently rotatable the kelly K may be moved vertically while being driven with a minimum of friction and resistance. Accordingly, the tool or tools operated on the drilling string may be evenly and smoothly advanced .and there is a minimum of additional load placed on the rotary table T when the kelly K is fed downwardly. When the rotary table T is rotated in the reverse direction or the direction opposite to that indicated by the arrow in Fig. 3 the surfaces 36 of the rollers I1 come into contact with the surfaces II o-f the kelly K. These tapered surfaces 36 of the roller I1 are pitched to have full engagement with the surfaces of the kelly for the dependable positive transmission of the rotative forces to the kelly,

The rollers I1 of the bushing provided by the present invention are mounted and formed to have long or extensive surfaces in driving contact with the flat surfaces of vthe kelly K as distinguished from the prior devices which usually have only point or line contact with the kelly. The extensive engagement between the rollers I1 and the kelly K materially reduces wear of the rollers and kelly and prevents the kelly from becoming grooved or Worn oi at its corners. Further, the tapered rollers of the present invention are longer lived than the cylindrical rollers heretofore employed.

Having described only a typical preferred form and application of my invention, I do not Wish to be limited or restricted to the specific details herein set forth, but Wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall Within the scope of the following claims:

Having described my invention, I claim:

l. A bushing for use in a rotary table for engaging a polygonal drill stem extending therethrough, said bushing including, a body for arrangement in the table and having recesses opposing the side surfaces o-f the drill stern, the central vertical axes of the recesses being offset from the central vertical axes of the opposing side surfaces of the drill stem, and rollers mounted in the recesses for rotation about substantially horizontal axes, each of said rollers having tapered surfaces of unequal lengths joining at a plane coincident with the central vertical axis of the adjacent side surface of the drill stem for cooperating with the drill stem to transmitI driving forces thereto.

2. A bushing for use in a rotary table for transmitting rotation to a polygonal drill stem extending through the table, said bushing including, a body for arrangement in the table, a plurality of rollers supported in the body for rotation, surface parts on said rollers normally receiving the drill stem with clearance and being in the same vertical planes as the central vertical axes of the adjacent side surfaces of the drill stem, and surfaces of unequal lengths on said rollers tapering from said parts to fully bear on the sides of the stem when the table is rotated.

3. A bushing for use in a rotary table for transmitting rotation to a polygonal drill stem extending through the table, said bushing including, a body for arrangement in the table, a plurality of rollers supported in the body for rotation, each of said rollers having a surface part normally receiving the drill stem with clearance, and tapered surfaces of unequal lengths extending in opposite directions from said parts to cooperate With the sides of the drill stem when the table is rotated in opposite directions.

4. A bushing for use in a rotary table for transmitting rotation to a polygonal drill stem extending through the table, said bushing including, a body for arrangement in the table, a plurality of cages inserted in the body, each cage having a vertical recess opposing a side surface of the polygonal drill stem, the central vertical axes of the recesses being offset from the central vertical axes of the opposing side surfaces of the drill stem, means retaining the cages in the body, and a plurality of vertically spaced rollers rotatably supported by each cage for independent rotation in the recesses of the cages, each roller having a surface part unequally spaced between its ends and aligned With the central vertical axis of the adjacent side surface of the drill stem and having tapered surfaces extending in opposite directions from said surface part for contacting the drill stem.

WILLIAM A. VOCK. 

